Abstract:

A high sensitive technique of photoacoustic calorimetry is used in the study of the effect of H2O molecules adsorbed on the surface of an aluminum optical mirror on the absorption of radiation 266 nm. It was found that the addition of water vapor with partial pressures PH2O = 7,9 mbar and PH2O = 15 mbar to the dry air of atmospheric pressure increases the absorption of radiation 266 nm on the surface of the “dry” mirror by 12% and 21%, respectively. The results of numerical simulation of the transmittance of a multi-pass spectrophotometric cell indicate the extreme need to take into account the observed effect in the measurements of the absorption spectra of atmospheric air containing water vapor, using multi-pass cells.